Salamanders territoriality

Jaeger, R. G., Goy, J., Tarver, M., and Marquez, C., 1985, Salamander territoriality Pheromonal markers as advertisement by males,... 

Salamander territoriality Phermonal markers as advertisement by males, Anim. Behav., 34 in press. 

For experimental studies of terrestrial salamanders, territorial markers have been obtained in a number of ways. A common and simple collection technique is to introduce individual salamanders into small chambers lined with a damp substrate (typically either soil, paper towels, or filter paper) and allow the salamanders to mark the substrate with secretions and fecal pellets (Tristram 1977 McGavin 1978 Jaeger Gergits 1979 Dawley 1984a Keen et al. 1987 Anthony 1993 Graves 1994). The length of time allowed for marking is variable, but a period of several days to 1 week are common. 

Jaeger, R.G., J.M. Goy, M. Tarver, C.E. Marquez. 1986. Salamander territoriality pheromonal markers as advertisement by males. Anim. Behav. 34 860-864. 

Salamanders of the ambystomatid family may also use territorial marks. In contrast to red-backed salamanders, which are repelled by conspecific odors or fecal pellets (Jaeger and Gergits, 1979 Jaeger, 1986), spotted salamanders, Amhystoma maculatum, are attracted to paper towels on which conspecifics had lived for 4 days, whether the latter were familiar or unfamiliar (Ducey and Ritsema, 1988). 

Horne, E. A. and Jaeger, R. G. (1988). Territorial pheromones of female red-backed salamanders. Ethology 78,143. 

Jaeger, R. G. (1986). Pheromonal markers as territorial advertisement by terrestrial salamanders. In Chemical Signals in Vertebrates, vol. 4, ed. D. Duvall, D. Miiller-Schwarze, and R. M. Silverstein, pp. 191-203. New York Plenum. 

Mathis, A., Jaeger, R. G., Keen, W. H., Ducey, P. K., Walls, S. C., and Buchanan, B. W., 1995, Aggression and territoriality by salamanders and a comparison with the territorial behavior of fiogs, in Amphibian Biology Vol. 2 Social Behaviour, H. Heatwole and B. K. Sullivan, eds., Surry Beatty Sons, Chipping Norton New South Wales, Australia, pp. 634-676. 

Jaeger, R. G., Kaivarsky, D., and Shimizu, N., 1982, Territorial behaviour of the red-backed salamander Expulsion of intruders, Anim. Behav. 30 490-496. 

Jaeger, R. G., Schwarz, J., and Wise, S., 1995, Territorial male salamanders have foraging tactics attractive to gravid femaies, Anim. Behav. 49 633-639. 

Mathis, A., 1990, Territorial salamanders assess sexual and competitive informadon using chemical signals, Anim. Behav. 40 953-962. 

PHEROMONAL MARKERS AS TERRITORIAL ADVERTISEMENT BY TERRESTRIAL SALAMANDERS... 

Fraser (1976a, 1976b) examined two dissimilarly sized, sympatric species of salamanders in the mountains of Virginia Plethodon cinereus and jP. hoffmani. He found no evidence of direct competition for food, and as an alternative, he proposed that interspecific competition occurs for space. This was the first substantial indication that spacing behavior via territoriality might occur within or between species of salamanders. 

Nothing is known about the biochemistry of the pheromones used in territorial advertisement. This is unavoidably true partly because the study of territoriality in salamanders is so new, partly because the existence of pheromones has been inferred only from behavioral responses of individuals under experimental conditions, and partly because none of the glands producing the suspected pheromones have been conclusively identified. In short, there is so little background information about territorial pheromonal communication in salamanders that sophisticated studies probably will not be conducted for several years yet. 

Virtually all tests of territorial pheromones have involved the response of a receiver salamander in the presence or absence of presumed pheromones from a sender. Four basic experimental designs have been used. 

In their own territories, salamanders foraged as would be predicted from optimal foraging theory (Pyke, 1984). In territories of conspecifics. 

Two attempts have been made to identify the source of the pheromones used in territorial communication by salamanders. The first was by Simon and Madison (1984), using experimental procedure (4) and Plethodon cinereus. They provided each male salamander with a choice of two substrates, each marked with either fecal pellets or cloacal washes. On one side, the pellets (or washes) were the test animal s own on the other side, the pellets (or washes) were from a conspecific. None of the salamanders had prior experience with each other. For both pellets and washes, salamanders significantly chose their own marked substrates over those of conspecifics. This was the first indication that fecal pellets are used to place pheromones in territories. In addition, the data from cloacal washes suggest that pheromones are produced by glands in or around the cloaca, and are not a by-product of the chemical composition of the feces per se. 

The fourth case indicated no position bias in the experiment. These data demonstrate, then, that male salamanders of this species are not only attracted to areas marked with their own pheromones, but are repulsed (and threatened) by areas marked by pheromones of other males. Territorial advertisement is inferred from these data. Parallel tests with females are now being performed. 

In summary, virtually all of the information on territorial pheromones (through behavioral inferences of their existence) comes from single species, Plethodon cinereus. Evidence to date indicates that at least males (and perhaps females) place chemical substances on the substrate, that these substances are contained in fecal pellets and are produced in or near the cloaca (though other glandular sources are not ruled out), that these substances tend to deter intruders from entering a marked (territorial) area, and that the aggressive and submissive interactions of territorial residents and intruders are governed in part by these substances (and in part by visual displays). Thus, pheromones, whatever they are, are used by Plethodon cinereus (and perhaps other species of salamanders) to advertise territorial possession. 

Apparently the nares are the principal centers for receiving pheromonal information. Olfactory receptors in the nares are able to discriminate among a variety of odors in salamanders of the family Ambystomatidae (Kauer, 1974 Kauer and Moulton, 1974 Kauer and Shepherd, 1975, 1977). However, members of this family are not known to be territorial (Martin et al., in press). 

The purpose of this scant review of homing and courtship is to emphasize that salamanders produce a variety of pheromones, probably from a variety of glands, and having a diversity of functions. However, there is not a single case where the composition and origin of a pheromone is well known, a factor that severely inhibits the study of pheromonal communication during territorial defense by salamanders. 

Gergits, W. F., 1982, Interference Competition and Territoriality Between the Terrestrial Salamanders Plethodon cinereus and Plethodon Shenandoah, M, S. Thesis, State University of New York at Albany, Albany. 

---